1. Field of the Invention
This invention relates to an integrated composite head of a magneto-resistance effect (MR) type head and an inductive (Ind) type head.
2. Description of the Prior Art
A magneto-resistance type magnetic head is superior in short wavelength sensitivity and has been and is being progressively employed as various magnetic heads such as, for example, a reproducing magnetic head of a magnetic recording and reproducing head for a hard disk drive. Various composite heads have been proposed wherein recording is performed by a conventional inductive type head and reproduction is performed by a magneto-resistance type head. An exemplary one of conventional magneto-resistance/inductive composite magnetic heads is shown in FIG. 3 which has one-gap construction wherein a magnetic gap is common to component magnetic heads.
Referring to FIG. 3, the magneto-resistance/inductive composite magnetic head shown includes first and second thin film magnetic cores 11 and 12 stacked, for example, on a floating slider or the like itself or on a base plate 6 mounted on such floating slider or the like such that a magnetic gap g is defined between front end portions thereof at a contacting or opposing face of the magnetic head to a magnetic record medium, that is, at an ABS surface (air bearing surface) 5 of the magnetic head. At least an end of a magneto-resistance effect element 13 formed from a magneto-resistance effect thin film or an electrode 14a of the magneto-resistance effect element 13 is disposed in the magnetic gap g and is exposed at the ABS surface 5. The electrode 14a and the other electrode 14b of the magneto-resistance effect element 13 are each formed from a conductive thin film. A bias conductor 15 is disposed across the magneto-resistance effect element 13 by way of an insulating layer 16. When the bias conductor 15 is energized, it provides a magnetization condition of a required direction to the magneto-resistance effect element 13 so that the magneto-resistance effect element 13 may operate in a characteristic region wherein the magneto-resistance characteristic thereof exhibits a superior linearity and a high sensitivity. A head winding 17 is formed in a spiral pattern such that it may pass a magnetic coupling portion between the first and second thin film magnetic cores 11 and 12, for example, at individual rear portions. The bias conductor 15 and the head winding 17 are each formed from a conductive thin film. A protective film 22 is provided to cover over the elements described above.
In this manner, a magneto-resistance type magnetic head having a so-called shield type construction wherein the magneto-resistance effect element 13 is disposed between the first and second thin film magnetic cores 11 and 12 is constructed while an inductive type magnetic head wherein the head winding 17 is wound on a magnetic path composed of the first and second thin film magnetic cores 11 and 12, and a magneto-resistance/inductive composite magnetic head wherein the magnetic gap g is common to the magneto-resistance type magnetic head and the inductive type magnetic head is constructed.
In the magneto-resistance/inductive composite magnetic head, each of the thin film magnetic cores 11 and 12 functions as a shield for the magneto-resistance effect element 13 upon reproduction and as an induction core upon recording, and further functions, particularly upon reproduction, as a magnetic path of a bias magnetic field produced by energization of the bias conductor with a dc current.
With the conventional magneto-resistance/inductive type composite magnetic head of the construction described above, however, if the integrated composite magnetic head is used as an inductive type recording head to effect recording in a condition wherein a reproduction output of such a waveform as shown in FIG. 4A is obtained when the integrated composite magnetic head is used as a magneto-resistance type head to effect reproduction and then the integrated composite head is used as a magneto-resistance type head again to effect reproduction, then a reproduction waveform different from that shown in FIG. 4A is sometimes obtained as shown in FIG. 4B, resulting in variation in reproduction characteristics of the integrated composite magnetic head. This arises from the fact that the magnetic domain construction of the thin film magnetic cores is varied by a magnetic field induced by a recording current, which varies the permeability of the magnetic cores to vary the bias magnetic field strength. Consequently, the reproduction sensitivity of the magneto-resistance effect element 13 is varied, which deteriorates the reliability of the integrated composite magnetic head.
Meanwhile, an improved magneto-resistance type magnetic head having a stabilized reproduction output characteristic has been proposed by the assignee of the present patent application and is disclosed in Japanese Patent Laid-Open Application No. 60-47223. In the magnetic head, in a no-signal magnetic field condition before starting of a reproducing operation, an attenuating current is supplied to an energization portion for generating a bias magnetic field at a bias conductor, that is, a magneto-resistance effect element so as to start reproduction in a fixed magnetization condition in order to reduce the hysteresis characteristic of the reproduction output to stabilize the output and reduce Barkhausen noise.
With the magnetic head, however, since an attenuating current is supplied to the bias conductor, an energization current which can achieve sufficient demagnetization cannot be obtained. In this instance, while there is a demagnetization effect for the magneto-resistance effect element, a sufficient demagnetization effect cannot be obtained for components of the magnetic path such as the thin film magnetic cores. As a result, stabilization of the magnetic characteristics of the magnetic head as a whole cannot be achieved.